One and a half moves

If you are just starting out in chess, or trying to teach other people how to play well, then simply looking one and a half moves ahead might be all you need to focus on. This is the system recommended by Charles Hertan in his book "Power Chess for Kids", and like a lot of good ideas, its strength is in its simplicity.
The subtitle of the book is "Learn how to think ahead and become one of the best players in your school", and clearly shows the market he is after.
I am often surprised at the number of new players who seem to focus on complicated opening theory, or 5 move combinations, when simply finding the one mover's is enough. In Hertan's book he even makes it simpler than that, by suggesting you focus on finding the third move in a capturing sequence  (which he calls 'takes, takes, bang!'). And based on my own experience, this is not only a step up from 'I move, ... ,then I move again', but would result in vastly improved results from your average school chess player.